DiGate R J, Marians K J
Program in Molecular Biology, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
J Biol Chem. 1992 Oct 15;267(29):20532-5.
Relaxation of superhelical DNA by Escherichia coli topoisomerase III (Topo III) was inhibited by the inclusion of tRNA in the reaction mixture. Investigation of the basis of this inhibition revealed that Topo III could bind RNA and establish a cleavage-religation equilibrium. The addition of SDS to these reaction mixtures induced cleavage of the RNA by Topo III. The nucleotide sequences of RNA and DNA cleavage sites were identical, although cleavage site preference differed. Thus, the possibility that Topo III can pass strands of RNA as well as strands of DNA must be considered in accounting for the role of this enzyme in nucleic acid metabolism.
在反应混合物中加入tRNA会抑制大肠杆菌拓扑异构酶III（Topo III）对超螺旋DNA的松弛作用。对这种抑制作用的基础进行研究发现，Topo III能够结合RNA并建立切割-连接平衡。向这些反应混合物中加入SDS会诱导Topo III切割RNA。RNA和DNA切割位点的核苷酸序列相同，尽管切割位点偏好有所不同。因此，在解释该酶在核酸代谢中的作用时，必须考虑Topo III能够穿过RNA链以及DNA链的可能性。
